A major stumbling block for the implementation of Mexico's Global Development Plan has been the country's large rural population of Indians. One government strategy to integrate this sector into the mainstream of society has been to teach Spanish, the official language, as a second language, while at the same time fostering ethnic pride. The exploratory study described here aimed to contribute to available research by analyzing factors in the success of second language programs. A causal model defined three social contexts directly affecting 33 Nahuatl children living in three rural hamlets in the state of Guerrero and enrolled in a pilot preschool Spanish program. The model included community, family, and school variables. By analyzing children's proficiency levels, the varying degrees to which several social variables influenced language learning progress were defined. The data, collected over a 1-year period, incorporated both qualitative and quantitative information. Findings indicated that, although all three conglomerates of variables affected language performance, the classroom environment was of the greatest relevance, with the home and village intervening indirectly in oral Spanish proficiency levels. This finding has strong implications for educators and language planners since it reconfirms the school's role in the success or failure of language policy. (Author/RH)